Frame Relay service is available from public carriers worldwide, and the first networks utilizing the technology were established in 1991. Frame Relay is a well-known transmission technology that employs variable-length packet switching and provides an efficient method for transmitting bursts of data. The technology has seen widespread use and acceptance in such applications as LAN (Local Area Network) internetworking, SNA migration, image processing, remote access connections and Internet connectivity. For example, Frame Relay is often used to transmit data from one LAN (Local Area Network) to another LAN over a WAN (Wide Area Network) since the transmission between LANs tends to be in bursts. Frame Relay provides the networking advantages of high speeds, low delay, port sharing and dynamic bandwidth allocation.
In certain Frame Relay networks, network instability may result where a Frame Relay exchange apparatus does not possess the necessary capacity to process PVC management frames with sufficient dispatch to avoid that a given Frame Relay transmission stream be declared inactive. This is of particular concern where a network irregularity occurs in a Frame Relay network having thousands of connections, since incoming asynchronous status messages will be transmitted simultaneously by each affected device to the Frame Relay exchange apparatus. This may overburden the timely handling of PVC management frames by the apparatus, which will result in a false declaration of inactivity for the Frame Relay streams otherwise unaffected by the network irregularity.
Frame Relay and ATM networks each have distinct advantages and characteristics. It is therefore expected that the use of both technologies will continue to be prevalent for some time. Consequently, there is a need to provide for interoperability between ATM users and Frame Relay users. When network users are interworked through both ATM and Frame Relay networks, such multiprotocol environments may be particularly prone to the network instability problem mentioned above. This occurs when the available processing rate of an interworking device, such as a frame exchange apparatus, is exceeded by the requirement to concurrently process PVC management frames both from the Frame Relay side and the ATM side of the multiprotocol network interface.
It is therefore an object of preferred embodiments of the present invention to provide a method and apparatus for the prioritization, multiple queuing and selective processing of PVC management frames in order to alleviate the problem of potential network instability in Frame Relay networks and Frame Relay/ATM hybrid networks. This and other objects of the present invention will be made apparent in the detailed description of embodiments of the invention which follows.